[RWebb]

KEH is more costly than eBay but allows no hassle returns and has been a good source for me over the last few decades...

speaking of the iPhone:
it sounds like Shaun will want a lot of depth of field (DOF) - that goes up as the sensor size goes down - a good phone cam will give a lot of DOF

focus stacking can be done in post for the D7200, but many Panasonic m43 cameras will do it in body - much easier and quicker - I moved almost entirely to Panny m43 a couple of years ago but still have some Nikon and Hasselblad gear

I also suggest light pipes, LEDs for adding light into small dark corners for macro

items can be placed on a piece of glass to make them seem to float in space

I use alligator clips or small clamps in a fixture for small items - stick them in front of the computer screen with a colored background (MS Word with paragraph formatted to the color you want) for tabletop photography of small things
- or drape a piece of burlap over the screen put it back a bit to blur the texture